/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.type.filter;

import java.lang.annotation.Annotation;
import java.lang.annotation.Inherited;

import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

/**
 * A simple filter which matches classes with a given annotation,
 * checking inherited annotations as well.
 *
 * <p>The matching logic mirrors that of {@link java.lang.Class#isAnnotationPresent(Class)}.
 *
 * @author Mark Fisher
 * @author Ramnivas Laddad
 * @author Juergen Hoeller
 * @since 2.5
 */
public class AnnotationTypeFilter extends AbstractTypeHierarchyTraversingFilter {

    private final Class<? extends Annotation> annotationType;

    private final boolean considerMetaAnnotations;


    /**
     * Create a new AnnotationTypeFilter for the given annotation type.
     * This filter will also match meta-annotations. To disable the
     * meta-annotation matching, use the constructor that accepts a
     * '{@code considerMetaAnnotations}' argument. The filter will
     * not match interfaces.
     *
     * @param annotationType the annotation type to match
     */
    public AnnotationTypeFilter(Class<? extends Annotation> annotationType) {
        this(annotationType, true, false);
    }

    /**
     * Create a new AnnotationTypeFilter for the given annotation type.
     * The filter will not match interfaces.
     *
     * @param annotationType the annotation type to match
     * @param considerMetaAnnotations whether to also match on meta-annotations
     */
    public AnnotationTypeFilter(Class<? extends Annotation> annotationType, boolean considerMetaAnnotations) {
        this(annotationType, considerMetaAnnotations, false);
    }

    /**
     * Create a new {@link AnnotationTypeFilter} for the given annotation type.
     *
     * @param annotationType the annotation type to match
     * @param considerMetaAnnotations whether to also match on meta-annotations
     * @param considerInterfaces whether to also match interfaces
     */
    public AnnotationTypeFilter(Class<? extends Annotation> annotationType, boolean considerMetaAnnotations,
            boolean considerInterfaces) {
        super(annotationType.isAnnotationPresent(Inherited.class), considerInterfaces);
        this.annotationType = annotationType;
        this.considerMetaAnnotations = considerMetaAnnotations;
    }

    /**
     * Return the {@link Annotation} that this instance is using to filter
     * candidates.
     *
     * @since 5.0
     */
    public final Class<? extends Annotation> getAnnotationType() {
        return this.annotationType;
    }

    @Override
    protected boolean matchSelf(MetadataReader metadataReader) {
        AnnotationMetadata metadata = metadataReader.getAnnotationMetadata();
        return metadata.hasAnnotation(this.annotationType.getName()) ||
                (this.considerMetaAnnotations && metadata.hasMetaAnnotation(this.annotationType.getName()));
    }

    @Override
    @Nullable
    protected Boolean matchSuperClass(String superClassName) {
        return hasAnnotation(superClassName);
    }

    @Override
    @Nullable
    protected Boolean matchInterface(String interfaceName) {
        return hasAnnotation(interfaceName);
    }

    @Nullable
    protected Boolean hasAnnotation(String typeName) {
        if (Object.class.getName().equals(typeName)) {
            return false;
        } else if (typeName.startsWith("java")) {
            try {
                Class<?> clazz = ClassUtils.forName(typeName, getClass().getClassLoader());
                return ((this.considerMetaAnnotations ? AnnotationUtils.getAnnotation(clazz, this.annotationType) :
                         clazz.getAnnotation(this.annotationType)) != null);
            } catch (Throwable ex) {
                // Class not regularly loadable - can't determine a match that way.
            }
        }
        return null;
    }

}
